Latency, Bandwidth Delay Product & TCP Window

This article highlights on the TCP/IP factors and concepts on networking, which decides the most favorable TCP Receive Window. The factors are Bandwidth Delay Product, Latency and the TCP Window. TCP Window represents quantity of data that is outstanding, which is not acknowledged by the receiver and is able to be in a network. Following the data amount being sent, the sending party has to stop and wait for confirmation from the receiving party that something has been received. Because of this, the value is perhaps the only important setting when tuning and adding speed to the broadband connection of the internet. When the ‘handshake’ stage of the TCP begins, there is the negotiation of the TCP Receive Window every time.

The unique standard of the DARPA of TCP/IP has the RWIN or TCP Window, which limits at 64K. This is because the headers of TCP has 16-bits only for the value of RWIN, as well as 2^16=64K. The limits had to be attended to and the year 1992, saw a ‘TCP Options’ header annex, added by the RFC 1323, which permitted the expansion of the maximum size of the TCP Window, by including another byte to be like a ‘scale factor’ to the value of the RWIN. Latent or RTT is the rate of each data transfer, the same as TCP being largely determinable by the speed.

Additionally, the delay should be considered or the Round Trip Time, RTT, of every data packet. Every occasion a client PC requests a question to a server, there is the delay of the RTT until a response has been received. Data packets travel via several routers that have high traffic, which are sometimes congested and the light speed is always a limitation. The major distance on Internet communication is also considered. Bandwidth Delay Product or in short known as BDP, verifies the data amount that may be in movement in a network, the same as the RWIN.

The BDP is a bandwidth available product as well as the RTT or latency. It is a concept that is very important in a protocol that is window-based like the TCP, in the same way the throughput is obligated by this BDP. The TCP Window and the BDP limit the bandwidth connection and the latency of the product. The latency/RWIN value cannot be exceeded by a transmission. To be able to determine an optimal TCP Receive Window, utilize simply on of the recommended values of the SG TCP Analyzer.